Backplane substrate and flexible display using the same

ABSTRACT

Disclosed are a backplane substrate, which achieves improved interface bonding characteristics via a recess configuration at the interface of an organic layer with an inorganic layer, thereby preventing peeling due to repeated folding, and a flexible display using the same. An organic layer is introduced into a recess provided in an inorganic layer so as to achieve improved interface bonding characteristics.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2016-0143981, filed Oct. 31, 2016, which is herebyincorporated by reference as if fully set forth herein.

BACKGROUND Technical Field

The present disclosure relates to a backplane substrate, and moreparticularly, to a backplane substrate, which achieves improvedinterface bonding characteristics via a recess configuration at theinterface of an organic layer with an inorganic layer, therebypreventing peeling due to repeated folding, and a flexible display usingthe same.

Description of the Related Art

Concrete examples of a flat panel display device may include, forexample, a liquid crystal display (LCD) device, an organiclight-emitting display (OLED) device, a plasma display panel (PDP)device, a quantum dot display device, a field emission display (FED)device, and an electrophoretic display (EPD) device. These devices arealike in that they necessarily require a flat display panel thatrealizes an image. Such a flat display panel has a configuration inwhich a pair of transparent insulation substrates is bonded to face eachother with an inherent luminous or polarizing material or some otheroptical material layer therebetween.

With the recent increase in the size of display devices, a demand for aplanar display device that occupies a small volume of space isincreasing. As this demand grows, recently, there is a demand for usingthe planar display device in a flexible form.

A flexible display is gradually thinning and developing to a foldableform. However, flexible displays to date have shown various problems,such as damage to a folding portion as a folding operation is repeatedand the number of folding operations is increased. For example, highphysical stress upon folding causes damage to pixels in a folding area,preventing the folding portion from being turned on at all. Even ifturn-on failure due to repeated folding does not occur, the repeatedfolding causes variation in a capacitance value of each sub-pixel astime passes, which results in deterioration in image quality.

In addition, the flexible display undergoes peeling at the interface,which develops poor bonding characteristics as folding is repeated, andthe prevention thereof is structurally difficult. In particular, once aportion begins to peel off, the entire interface may be separated due tofolding, with the peel-off starting point as a seed, which is a majorproblem that deteriorates reliability.

BRIEF SUMMARY

Accordingly, the present disclosure is directed to a backplane substrateand a flexible display using the same that substantially obviate one ormore problems due to limitations and disadvantages of the related art.

An object of the present disclosure is to provide backplane substrate,which achieves improved interface bonding characteristics via a recessconfiguration at the interface of an organic layer with an inorganiclayer, thereby preventing peeling due to repeated folding, and aflexible display using the same.

Additional advantages, objects, and features of the disclosure will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of thedisclosure. The objectives and other advantages of the disclosure may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

The present disclosure relates to a backplane substrate and a displaydevice using the same, in which an adhesion recess is provided in aninorganic layer stack under an organic layer so that the organic layerhas a wide contact area with the inorganic layer stack through theadhesion recess, whereby peeling of the organic layer is prevented, andconsequently, reliability with respect to repeated folding operations isimproved.

To achieve these objects and other advantages and in accordance with thepurpose of the disclosure, as embodied and broadly described herein, abackplane substrate includes a flexible base substrate in which anactive area having a plurality of sub-pixels is defined in a centerthereof and a dummy pixel portion having dummy pixels, which areprovided respectively in the same line as the pixels, is defined alongan edge of the active area, an organic layer configured to cover boththe dummy pixels and the sub-pixels, and an inorganic layer stackconfigured to be in contact with the organic layer thereabove over atleast the dummy pixels, the inorganic layer stack having a plurality ofadhesion holes or recesses, into which the organic layer is introduced,namely, when the organic layer is formed, a portion of it is formed inthe adhesion recess.

The adhesion recesses in the inorganic layer stack may have a greaterdiameter at a lower side thereof than at an upper side thereof. Inaddition, the organic layer may be in contact with a lateral side and abottom of each adhesion recess.

In addition, the inorganic layer stack may include a first wire and asecond wire located in different layers so as to overlap each other, anda first interlayer insulation layer located between the first and secondwires.

The adhesion recess provided in the first wire may have a greaterdiameter than the adhesion recess provided in the second wire. In thiscase, the first wire may have a different etch selectivity than thesecond wire.

In addition, the backplane substrate may further include a third wirelocated on an upper side of the second wire so as to overlap the secondwire, and a second interlayer insulation layer between the second wireand the third wire. In this case, the adhesion recess provided in thefirst wire may have a greater diameter than the adhesion recess providedin the second wire and the third wire. Here, the second wire and thethird wire may have a different etch selectivity than the first wire.

The inorganic layer stack may further include a plurality ofsub-adhesion recesses in the sub-pixels.

In accordance with another aspect of the present disclosure, a flexibledisplay includes a first flexible base substrate in which an active areahaving a plurality of sub-pixels is defined in a center thereof and adummy pixel portion having dummy pixels, which are provided respectivelyin the same line as the pixels, is defined along an edge of the activearea, a second flexible base substrate configured to be opposite thefirst flexible base substrate and having a touch wire, an adhesive layerprovided between the first and second flexible base substrates, anorganic layer provided on at least one of the first flexible basesubstrate and the second flexible base substrate so as to correspond tothe dummy pixels and the sub-pixels, and an inorganic layer stackconfigured to be in contact with the organic layer thereabove over atleast the dummy pixels, the inorganic layer stack having a plurality ofadhesion recesses, into which the organic layer is introduced.

In addition, the organic layer and the inorganic layer stack may beprovided on the first flexible base substrate.

The organic layer and the inorganic layer stack may be additionallyprovided on the second flexible base substrate.

The adhesion recesses in the inorganic layer stack may have a greaterdiameter at a lower side thereof than at an upper side thereof.

The inorganic layer stack may include wires provided in two or moredifferent layers, and an interlayer insulation layer provided betweenthe wires.

Here, the organic layer may be in contact with a lateral side and abottom of each adhesion recess.

The inorganic layer stack may further include a plurality ofsub-adhesion recesses in the sub-pixels.

It is to be understood that both the foregoing general description andthe following detailed description of the present disclosure are exampleand explanatory and are intended to provide further explanation of thedisclosure as claimed.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the disclosure andtogether with the description serve to explain the principle of thedisclosure. In the drawings:

FIG. 1 is a plan view illustrating a backplane substrate according tothe present disclosure;

FIG. 2 is a circuit diagram of a sub-pixel illustrated in FIG. 1;

FIGS. 3A and 3B are a schematic cross-sectional view and a schematicplan view of the backplane substrate according to the presentdisclosure;

FIG. 4 is a process flowchart illustrating a method of manufacturing thebackplane substrate according to the present disclosure;

FIG. 5 is a plan view illustrating a dummy pixel of the backplanesubstrate according to the present disclosure;

FIG. 6 is a plan view illustrating a sub-pixel of the backplanesubstrate according to the present disclosure;

FIGS. 7A and 7B are plan views illustrating several embodiments of anadhesion recess in the dummy pixel of the backplane substrate accordingto the present disclosure;

FIG. 8 is a cross-sectional view taken along line I-I′ of FIG. 7A;

FIG. 9 is a cross-sectional view taken along line II-II′ of FIG. 7B;

FIG. 10 is a plan view illustrating a touch substrate of a flexibledisplay according to the present disclosure; and

FIG. 11 is a cross-sectional view illustrating the flexible displayaccording to the present disclosure.

DETAILED DESCRIPTION

The advantages and features of the present disclosure and the way ofattaining them will become apparent with reference to embodimentsdescribed below in detail in conjunction with the accompanying drawings.The present disclosure, however, are not limited to the embodimentsdisclosed hereinafter and may be embodied in many different forms.Rather, these example embodiments are provided so that this disclosurewill be through and complete and will fully convey the scope to thoseskilled in the art. The scope of the present disclosure should bedefined by the claims.

In the drawings for explaining the example embodiments of the presentdisclosure, for example, the illustrated shape, size, ratio, angle, andnumber are given by way of example, and thus, are not limited to thespecification or figures of the present disclosure. Throughout thepresent specification, the same reference numerals designate the sameconstituent elements. In addition, in the following description of thepresent disclosure, a detailed description of known functions andconfigurations incorporated herein will be omitted when it may make thesubject matter of the present disclosure rather unclear. The terms“comprises,” “includes,” and/or “has,” used in this specification, donot preclude the presence or addition of other elements unless it isused along with the term “only.” The singular forms “a,” “an,” and “the”are intended to include the plural forms as well, unless the contextclearly indicates otherwise.

In the interpretation of constituent elements included in the variousembodiments of the present disclosure, the constituent elements areinterpreted as including an error range even if there is no explicitdescription thereof.

In the description of the various embodiments of the present disclosure,when describing positional relationships, for example, when thepositional relationship between two parts is described using “on,”“above,” “below,” “aside,” or the like, one or more other parts may belocated between the two parts unless the term “directly” or “closely” isused.

In the description of the various embodiments of the present disclosure,when describing temporal relationships, for example, when the temporalrelationship between two actions is described using “after,”“subsequently,” “next,” “before,” or the like, the actions may not occurin succession unless the term “directly” or “just” is used.

In the description of the various embodiments of the present disclosure,although terms such as, for example, “first” and “second” may be used todescribe various elements, these terms are merely used to distinguishthe same or similar elements from each other. Therefore, in the presentspecification, an element modified by “first” may be the same as anelement modified by “second” within the technical scope of the presentdisclosure unless otherwise mentioned.

The respective features of the various embodiments of the presentdisclosure may be partially or wholly coupled to and combined with eachother, and various technical linkage and driving thereof are possible.These various embodiments may be performed independently of each other,or may be performed in association with each other.

*Backplane Substrate*

A backplane substrate, which will be described below, is a configurationin which a thin-film transistor array and an organic light-emittingarray are provided on a flexible base substrate. In some cases, thebackplane substrate also refers to a configuration in which only athin-film transistor array, excluding an organic light-emitting array,is included. Such a backplane substrate includes a plurality ofsub-pixels, and enables gradation for respective sub-pixels.

In addition, the backplane substrate of the present disclosure has astructure that exhibits excellent folding reliability when applied to aflexible display, but is not limited in the application to the flexibledisplay, and may be applied to any other flat panel display device. Inthis case, the base substrate used therein may be any one of a glasssubstrate and a plastic substrate.

FIG. 1 is a plan view illustrating a backplane substrate according tothe present disclosure, and FIG. 2 is a circuit diagram of a sub-pixelillustrated in FIG. 1.

As illustrated in FIG. 1, in the backplane substrate 1000 of the presentdisclosure, an active area AA having a plurality of sub-pixels SP isdefined in the center thereof, and a dummy pixel portion DA1 having oneor more dummy pixels DP provided in the same line as the pixels SP isdefined along the edge of the active area AA. The dummy pixels DP may beprovided in a number of ten or fewer at opposite sides or the upper andlower sides of the active area AA, in order to avoid deterioration inresolution.

The portion of the backplane substrate 1000 outside the active area AAis a non-display area DA. The non-display area DA includes theabove-described dummy pixel portion DA1 and a dead area DA2. The deadarea DA2 includes scan drivers SD1 and SD2 located at the outer side ofthe dummy pixel portion DA1 at opposite sides of the active area AA, anda pad portion 60 provided on one side of the outer periphery of theactive area AA, the pad portion 60 having a plurality of pad electrodes.In addition, a circuit board (not illustrated) may be connected to thepad electrodes of the pad portion 60 in the dead area DA2.

The scan drivers SD1 and SD2 may be provided in a built-in form to havea plurality of thin-film transistors for each line, in the same processas that for forming thin-film transistors in the active area AA.However, the backplane substrate of the present disclosure is notlimited thereto, and in addition to the built-in-type scan drivers SD1and SD2, a separate scan driver may be provided in a chip-on-film form.

In the backplane substrate 1000, a folding axis thereof is defined in agiven direction. The folding axis corresponds to a bending location ofthe flexible display.

The backplane substrate of the present disclosure is changed in thestructure of the dummy pixel DP and/or the sub-pixel SP so as to preventpeeling at the region at which an organic layer material and aninorganic layer material meet each other in a display device thatundergoes repeated folding, and includes a adhesion recess in aninorganic layer at the interface of the inorganic layer with an organiclayer.

FIG. 2 is a circuit diagram of the sub-pixel in the active area AAaccording to an example. Each sub-pixel of the active area AA includes acircuit unit including at least one or more thin-film transistors S-Trand D-Tr, a storage capacitor Cst, and an organic light-emitting diodeOLED connected to the storage capacitor Cst and the thin-film transistorD-Tr.

FIG. 2 illustrates an example in which two thin-film transistorsincluding a selection thin-film transistor S-Tr and a driving thin-filmtransistor D-Tr are provided, and any other thin-film transistor may beadded as needed. Among these, the driving thin-film transistor D-Tr iselectrically connected to a first electrode of the organiclight-emitting diode OLED, and the storage capacitor Cst is connectedbetween a gate electrode of the driving thin-film transistor D-Tr and aconnection end at which the driving thin-film transistor D-Tr isconnected to the first electrode of the organic light-emitting diodeOLED. The connection end may be a source electrode or a drain electrodeof the driving thin-film transistor D-Tr. When the connection end is thedrain electrode, the source electrode is connected to a driving currentline VDL and receives a driving voltage. When the connection end is thesource electrode, the drain electrode is connected to the drivingcurrent line VDL.

In addition, the circuit unit is provided between a gate line GL and adata line DL, which are located at the boundary of the sub-pixel andcross each other. The driving current line VDL is parallel to the dataline DL and is spaced apart from the data line DL of a neighboringsub-pixel. The selection thin-film transistor S-Tr is provided betweenthe gate line GL and the data line DL and is connected to the gateelectrode of the driving thin-film transistor D-Tr, which is connectedto the storage capacitor Cst, so that a predetermined sub-pixeltransfers current to the organic light-emitting diode OLED via thedriving thin-film transistor D-Tr according to the selective driving ofthe selection thin-film transistor S-Tr, thereby performing on/offcontrol of the organic light-emitting diode OLED.

In addition, a thin-film transistor of a gate circuit block is formed ina shape the same as or similar to that of the selection thin-filmtransistor or the driving thin-film transistor.

Hereinafter, the principle whereby the interface characteristics oforganic and inorganic layers of the present disclosure are improved willbe described with reference to the accompanying drawings.

FIGS. 3A and 3B are a schematic cross-sectional view and a schematicplan view of the backplane substrate according to the presentdisclosure.

As illustrated in FIGS. 3A and 3B, the backplane substrate according tothe present disclosure includes, provided on the flexible base substrate100 in which the active area AA having the plurality of sub-pixels SP isdefined in the center and the dummy pixel portion DA1 having the dummypixels DP is defined along the edge of the active area AA as illustratedin FIG. 1, an organic layer 1900, which covers both the dummy pixels DPand the sub-pixels SP, and an inorganic layer stack 1800, which is incontact with the bottom of the organic layer 1900 over at least thedummy pixels DP and has a plurality of adhesion recesses 1800 a, intowhich a portion of the organic layer 1900 is formed.

The adhesion recesses 1800 a in the inorganic layer stack 1800 have adiameter greater at the lower side thereof than at the top thereof. Assuch, when the organic layer 1900 is applied onto the inorganic layerstack 1800 having the adhesion recesses 1800 a therein, the organiclayer 1900 is introduced into each adhesion recess 1800 a. The organiclayer, when formed, is conformal to the material on which it is formed,therefore, upon formation, portions of the organic layer are introducedinto the each recess 1800 a to cause the organic layer 1900 to be withineach recess. Accordingly, once the organic layer 1900 has been broughtinto contact with the lateral side and the bottom of the adhesion recess1800 a, even if the strength of the adhesion bond of the organic layer1900 with the material of the stack 1800 is reduced, the adhesionholding force of layer 1900 within the recess 1800 a is not degraded.For for example, if external force applied thereto upon inward foldingor outward folding, the organic layer 1900, which has been cured in theadhesion recess 1800 a, remains coupled to layer 1800, rather than beingpeeled off upward, owing to the structure of the adhesion recess 1800 ahaving the narrow upper side and the wide lower side. In this way,peeling off of the organic layer 1900 from the inorganic layer stack1800 is prevented.

Meanwhile, reference numeral 1200 designates another inorganic layerdisposed under the inorganic layer stack 1800, and is an inorganicbuffer layer having a buffer function on the base substrate 100.

In one embodiment, the inorganic layer stack 1800 may include, forexample, metals of two or more different layers and may attain aninversely tapered structure, in which the upper side has a greaterdiameter than the lower side, using a difference in etch selectivity. Inthis case, the inorganic buffer layer 1200 may protect, for example, thebase substrate 100 thereunder in a metal removal process. In oneembodiment, all layers and sublayers of the inorganic stack 1800 arecomprised of inorganic materials, but in a second embodiment, theinorganic stack 1800 may include one or more layers or sublayers oforganic material that are included within the stack. Namely, it is notrequired in the second embodiment that each sub-layer within stack 1800be composed solely of inorganic material. Meanwhile, the inorganic layerstack 1800 has the plurality of adhesion recesses 1800 a therein, andone or more adhesion recesses 1800 a may be provided for every dummypixel DP.

Hereinafter, an example of forming the adhesion recesses 1800 a in thebackplane substrate of the present disclosure will be described withreference to the manufacturing method.

FIG. 4 is a process flowchart illustrating a method of manufacturing thebackplane substrate according to the present disclosure. In addition,FIG. 5 is a plan view illustrating the dummy pixel of the backplanesubstrate according to the present disclosure, and FIG. 6 is a plan viewillustrating the sub-pixel of the backplane substrate according to thepresent disclosure. In addition, FIGS. 7A and 7B are plan viewsillustrating several embodiments of the adhesion recesses in the dummypixel of the backplane substrate according to the present disclosure,FIG. 8 is a cross-sectional view taken along line I-I′ of FIG. 7A, andFIG. 9 is a cross-sectional view taken along line II-II′ of FIG. 7B.

The method of manufacturing the backplane substrate of the presentdisclosure is performed in the following sequence.

First, after a sacrificial layer (not illustrated) is formed on a glasssubstrate (not illustrated), the flexible base substrate 100 is formedon the sacrificial layer.

The flexible base substrate 100, which, in the final assembly,constitutes the backplane substrate 1000 of FIG. 1, is a flexibleplastic film, which may include one or more polymer compounds selectedfrom among the group consisting of polyester or a copolymer includingpolyester, polyimide or a copolymer including polyimide, an olefin-basedcopolymer, polyacrylic acid or a copolymer including polyacrylic acid,polystyrene or a copolymer including polystyrene, polysulfate or acopolymer including polysulfate, polycarbonate or a copolymer includingpolycarbonate, polyamic acid or a copolymer including polyamic acid,polyamine or a copolymer including polyamine, polyvinylalcohol, andpolyallylamine. Here, the thickness of the flexible base substrate 100ranges from 5 μm to 150 μm. The thickness of the flexible base substrate100 may be 50 μm or less.

In the following description related to the formation of respectivecomponents, the respective components are assumed as being formed on theentire flexible base substrate 100 and the formation area thereof is notlimited to the active area AA or the dead area DA2 including the dummypixels DP unless specifically stated otherwise.

As illustrated in FIGS. 8 and 9, an inorganic buffer layer 110, which isin the form of a plurality of layers, and an active buffer layer 120 aresequentially formed on the base substrate 100. The inorganic bufferlayer 110, which is in the form of a plurality of layers, is provided toprotect a thin-film transistor array and an organic light-emitting arrayin the subsequent process of removing the glass substrate (notillustrated) under the base substrate 100.

Subsequently, after an amorphous silicon layer is deposited on theactive buffer layer 120 and is then crystallized into polysilicon usinga laser, the polysilicon is selectively removed to form an active layer130 (110S). The active buffer layer 120 may prevent foreign substancesof, for example, the glass substrate (not illustrated) from having aneffect on the active layer 130 upon deposition or laser crystallizationin the process of forming the active layer 130 (see FIG. 11), and mayprotect the active layer 130.

In one embodiment, the active layer 130 (see FIG. 11) may be provided toonly in those locations that correspond to the sub-pixels SP, and insome cases, may be provided in the locations of the dummy pixels DP aswell as the sub-pixels SP. In this embodiment, the active layer 130 isnot present adjacent to the recess 1800 a, as can be seen in FIGS. 8 and9.

Subsequently, a gate insulation layer 140 is formed on the active bufferlayer 120 and the active layer 130.

Subsequently, a first metal is deposited on the gate insulation layer140 and is selectively removed to form a plurality of first wires 155 ina line direction (see reference character GL in FIG. 2)(120S). A gateelectrode (not shown in the Drawings) of each of the thin filmtransistor may be integrally formed in the same layer as the first wires155 in each sub-pixel SP. The first wires 155 refer to all wires formedin the same line direction, and may be provided to correspond to thesub-pixels SP. In addition, the first wires 155 may be formed across thesub-pixels to extend to the dummy pixels so as to be electricallyconnected to the scan drivers SD1 and SD2. For example, the first wires155 may include the gate line GL of FIG. 2. In some cases, when acircuit configuration provided in the sub-pixel has an additionalcomponent compared to the basic configuration of FIG. 2, the first wires155 may further include, for example, a scan line SL, in addition to thegate line GL. A first storage electrode 155 a of the storage capacitormay be formed in the same layer as the first wires 155 using the samemetal.

Subsequently, an interlayer insulation stack 160, which includes aplurality of interlayer insulation layers 160 a and 160 b, is formed onthe gate insulation layer 140 on which the first wires 155 have beenformed. Specifically, when forming the interlayer insulation stack 160,after a first interlayer insulation layer 160 a is formed, an auxiliarystorage electrode 165 is formed, and subsequently, a second interlayerinsulation layer 160 b is formed. Thereby, an electrode component, whichfunctions as an electrode of the storage capacitor, may be providedbetween interlayer insulation layers.

Subsequently, the interlayer insulation stack 160 and the gateinsulation layer 140 are selectively removed to form contact holes CT,which expose a portion of the active layer 130 (130S).

Subsequently, a second metal is deposited on the interlayer insulationstack 160 having the contact holes CT therein and is then selectivelyremoved to form second wires 175 and 170 in a direction crossing thefirst wires 155 (140S). A source electrode/a drain electrode 175 b (notshown in the Drawings) of each of the thin film transistor may beintegrally formed in the same layer as the second wires 175 in eachsub-pixel SP. Here, a portion of the second wires is connected to someof the contact holes. The second wires 170 may include the data line DLand the driving current line VDL of the circuit of the sub-pixelillustrated in FIG. 2. The second wires 175 may include a dummy dataline DL and a dummy driving current line VDL of the dummy pixel.

Alternatively, when an additional thin-film transistor or an additionalcapacitor is provided, compared to the circuit of FIG. 2, the secondwires 175 and 170 may further include an additional wire such as, forexample, a reference voltage line RL, in addition to the data line DLand the driving current line VDL. In addition, in some cases, a secondstorage electrode 175 a, which constitutes the storage capacitor, may beformed in the same layer as the second wires 175 and 170 in the sameprocess.

Meanwhile, the configuration from the active layer 130 to the secondwires 175 is referred to as a thin-film transistor array.

Subsequently, an inorganic passivation layer 180 is deposited on thesecond wires 175 and is then selectively removed to form first pixelcontact holes (not illustrated) (150S). Here, when forming the firstpixel contact holes, the adhesion recesses 1800 a are formed in thedummy pixel regions. Here, the material that is removed from theadhesion recesses 1800 a corresponds to a protective layer 180, thesecond wires 175, the second interlayer insulation layer 160 b, theauxiliary storage electrode 165, the first interlayer insulation layer160 a, and the first wires 155. This combined stack of layerscorresponds to the layer 1800 of FIG. 3A. In one embodiment, the sameetch steps and using the same mask that form the first pixel contactholes, the adhesion recesses 1800 a are formed. The use of the same maskand process steps to simultaneously form an electrical contact to thepixels and to form the adhesion recesses 1800 a saves time and thenumber of masks that are required.

As just described, the inorganic stack 1800 is comprised of a stack oflayers and sublayers. In one embodiment, each of these layers is made ofinorganic material. In a second embodiment, one or more of the layerscould include an organic material. For example, layers 160 and 180 arepreferably inorganic, but it is also permitted to include one or moreorganic components in layers 160 or 180 and still consider the stack1800 to be an inorganic stack. Thus, the meaning of the term inorganiclayer when referring to the multilayer stack 1800 permits one or more ofthe sublayers to include organic material in some embodiments.

In this case, the reason the adhesion recess 1800 a has an inverselytapered shape is because the second wires 175 have lower selectivity ofan etchant or dry gas than the first wires 155 or the auxiliary storageelectrode 165, and therefore, the first wires 155 or the auxiliarystorage electrode 155 having higher selectivity thereunder is etched toa greater diameter than the second wires 175.

Subsequently, an organic planarization layer 190 is applied onto theprotective layer 180 having the first pixel contact holes therein and isthen selectively removed to form second pixel contact holes (notillustrated), which are connected to the first pixel contact holes(160S). Since both the first and second pixel contact holes (notillustrated) expose a portion of the second wires 175 and 170, in thesubsequent process of forming a first electrode 200, the first electrode200 may be connected to a portion of the second wires 175 and 170, or tothe same layer as these wires, through the first and second pixelcontact holes.

Subsequently, for example, a third metal or metal oxide layer isdeposited on the planarization layer 190 having the second pixel contactholes therein and is selectively removed to form the first electrode 200(see FIG. 11), which is connected to the second wires 170 and 175through the first and second pixel contact holes (170S).

Subsequently, a bank 210 (see FIG. 11) is formed in an area of eachsub-pixel excluding an emission portion (180S).

Subsequently, an organic light-emitting layer 220 (see FIG. 11) isdeposited on the bank 210 (see FIG. 11) and on the first electrode 200including the emission portion.

Subsequently, a second electrode 230 (see FIG. 11) is formed on theorganic light-emitting layer 220 using a fourth metal or metal oxidelayer. The first electrode 200, the organic light-emitting layer 220 andthe second electrode 230 are referred to as the organic light-emittingdiode OLED.

In addition, the configuration from the first electrode 200 to thesecond electrode 230 is referred to as an organic light-emitting array.

An encapsulation layer 240 (see FIG. 11) is provided on the organiclight-emitting array in order to cover at least the sub-pixels SP and toprevent moisture permeation. Although a portion of the encapsulationlayer 240 may be provided in the dummy pixels, the encapsulation layer240 may be selectively provided in the dummy pixel portion because thedummy pixels have no layer that is vulnerable to moisture permeation,like the organic light-emitting layer.

Here, the configuration from the flexible base substrate 100 to theencapsulation layer 240 described above is referred to as the backplanesubstrate.

As illustrated in FIG. 5, the dummy pixel may have a contact-holeforming region C_H defined between the wires (i.e. the gate line GL, thedata line DL and the driving current line VDL), and may include a singleadhesion recess 1800 a or a plurality of adhesion recesses 1800 a in thecontact-hole forming region C_H. Since the dummy pixel has ananti-electrostatic function and is not actually used for illumination,the contact-hole forming region C_H located between the wires has alarge available area. Compared to this, the sub-pixel SP in the activearea AA needs to have a storage capacitor forming region STR between thewires. The sub-pixel SP may further have a sub-contact hole C_Hsubformed in a portion of the storage capacitor forming region STR, asillustrated in FIG. 6.

Although difference in bonding at the interface of inorganic and organiclayers due to, for example, folding may be observed in the entire area,this bonding difference may be the worst in the peripheral area.Therefore, in the backplane substrate of the present disclosure, it maybe more effective for the contact holes having an inversely taperedshape to be provided in the dummy pixel and to be additionally providedin the sub-pixel of the active area.

In addition, as illustrated in FIG. 7A or 7B, two or more wires 155 and175 or 155, 165 and 175 are located so as to overlap each other, and theadhesion recess 1800 a is formed to penetrate the wires.

FIGS. 7A and 8 illustrate the shape in which the adhesion recess 1800 ais provided in the first and second wires 155 and 175, the interlayerinsulation stack 160 between the first and second wires 155 and 175, andthe protective layer 180 above the second wire 175. The adhesion recess1800 a is formed by sequentially removing the protective layer 180, thesecond wire 175, the interlayer insulation layer 160, and the first wire155, and is defined simultaneously with the formation of the first pixelcontact recess in the protective layer 180.

FIGS. 7B and 9 illustrate the shape in which the adhesion recess 1800 ais provided in the first wire 155, the auxiliary storage electrode 165and the second wire 175, which overlap each other, the first and secondinterlayer insulation layers 160 a and 160 b therebetween, and theprotective layer 180 above the second wire 175. The adhesion recess 1800a is formed by sequentially removing the protective layer 180, thesecond wire 175, the second interlayer insulation layer 160 b, theauxiliary storage electrode 165, the first interlayer insulation layer160 a and the first wire 155, and is defined simultaneously with theformation of the first pixel contact recess in the protective layer 180.

Hereinafter, a flexible display using the above-described backplanesubstrate will be described.

*Flexible Display*

FIG. 10 is a plan view illustrating a touch substrate of a flexibledisplay according to the present disclosure, and FIG. 11 is across-sectional view illustrating the flexible display according to thepresent disclosure.

The flexible display of the present disclosure is configured in such amanner that the above-described backplane substrate and a touchsubstrate are bonded to each other.

As illustrated in FIGS. 10 and 11, the touch substrate includes aplurality of transmission parts Tx 320 and a plurality of transportparts Rx 330, which are disposed on an opposing base substrate 300 indirections crossing each other for touch detection. Here, eachtransmission part Tx is a block having therein a plurality of firsttouch wires 321, which are provided in a first direction and a seconddirection to cross each other. The first touch wires 321 have a latticeshape and are branched about the intersection thereof, rather than beingspaced apart from each other, in the same layer. When viewing the planarshape thereof, the first touch wires 321 are shaped such that thin wiresform a mesh in the area of the transmission part Tx. Likewise, eachtransport part Rx includes a plurality of second touch wires 331, whichare provided in a third direction and a fourth direction to cross eachother in a mesh shape. It will be appreciated that the third directionis the same direction as the first direction and the fourth direction isthe same direction as the second direction. However, the disclosure isnot limited thereto, and the third direction and the fourth direction ofthe second touch wires 331 may be set to be different from the firstdirection and the second direction of the first touch wires 321. Inaddition, although the first direction and the second direction may beorthogonal to each other as illustrated, the disclosure is not limitedthereto, and the angle therebetween may be modified to an acute angle oran obtuse angle.

Although the transmission part Tx and the transport part Rx areillustrated in the drawing as being arranged respectively in thehorizontal direction and the vertical direction, the disclosure is notlimited thereto. The transmission part Tx and the transport part Rx maybe arranged respectively at predetermined angles relative to thehorizontal direction, or may be set to be opposite those describedabove.

The plurality of first touch wires 321 included in the transmission partTx and the plurality of second touch wires 331 included in the transportpart Rx may be formed in the same layer using metal. In this case, inorder to prevent electrical short-circuit between the first and secondtouch wires 321 and 331 at the intersection area of the X-direction inwhich the transmission parts Tx are arranged and the Y-direction inwhich the transport parts Rx are arranged, only one of both the touchwires extends to pass through the intersection area and the other one iselectrically separated with a bridge electrode 340 of another layer. Asillustrated, a connection electrode 320 a, which is integrally formedwith the first touch wires 321 provided in the transmission part Tx, isprovided at the intersection area and is integrally formed withneighboring transmission parts Tx so as to interconnect the neighboringtransmission parts Tx. The bridge electrode 340 of another layer isprovided to cross the connection electrode 320 a and is connected to thesecond touch wires 331 of neighboring transport parts Rx. Meanwhile,although a single connection electrode 320 a may be provided at theintersection area, as illustrated, a plurality of connection electrodes230 a may be spaced apart from one another in the same direction. Therespective connection electrodes 320 a are connected to the first touchwires 321 of the neighboring transmission parts Tx in the form ofblocks.

In another embodiment, when the first touch wires 321 and the secondtouch wires 331, which respectively constitute the transmission part Txand the transport part Rx, are metal of different layers, the firsttouch wires 321 and the second touch wires 331 may respectively extendto the intersection area so as to interconnect neighboring transmissionparts Tx and to interconnect neighboring transport parts Rx, even if nobridge electrode of another layer is provided.

The reason why the transmission part Tx and the transport part Rx of thetouch substrate include the plurality of first touch wires 321 andsecond touch wires 331 in the form of a mesh is to increase sensitivityusing low-resistance metal without RC delay upon signal transmission andsignal detection, to prevent metal wires from being visible in a screenon which an image is displayed by finely dividing the metal wires, andto disperse stress due to folding or bending when used in a flexibleorganic light-emitting display device.

In addition, the metal, which forms the first touch wires 321 and thesecond touch wires 331, may be low-resistance metal such as, forexample, any one selected from among gold (Au), silver (Ag), palladium(Pd), copper (Cu), aluminum (Al), chrome (Cr), molybdenum (Mo) andtitanium (Ti) or a metal stack or a metal alloy including at least onethereof. In one example, the metal stack may be an Ag—Pd—Cu alloy (APC)or a Mo—Al—Mo alloy. However, the metal of the first and second touchwires 321 and 331 is not limited to the above enumerated examples, andmay be replaced with another low-resistance metal, or a metal alloy or ametal stack thereof.

Meanwhile, signals are sequentially transmitted to the transmissionparts Tx on a per-line basis, and the transport parts Rx perform signaldetection on a per-column basis. Here, there is variation in detectedsignals when a touch occurs, and whether or not a touch occurs isdetermined by detecting the variation.

The touch substrate of the present disclosure includes a touch electrodearray of the first touch wires 321 and the second touch wires 331described above on the flexible opposing base substrate 300. This touchsubstrate is bonded to the organic light-emitting array and performscoordinate input and detection functions during driving of an organicdisplay device.

The opposing base substrate 300 may be formed of plastic, thin glass ormetal. In addition, a first inorganic buffer layer 310 may be providedon the surface of the opposing base substrate 300 to provide an evenfilm forming surface on which the first and second touch wires 321 and331 are formed, and to protect a touch electrode array when asacrificial layer or a glass substrate under the opposing base substrate300 is removed for flexibility.

Meanwhile, the opposing base substrate 300 includes a center touch areaTA having the transmission parts Tx and the transport parts Rx arrangedin multiple lines and columns, and an outer peripheral dead area DA. Atouch pad portion 370 is provided in a portion of the dead area DA, androuting wires 350 a and 350 b are provided to extend from the ends ofthe respective transmission parts Tx and the respective transport partsRx to the touch pad portion 370. The routing wires 350 a and 350 b maybe in the same layer as the first and second touch wires 321 and 331described above, or may be in the same layer as the bridge electrode340.

The dead area DA corresponds to the outside of the touch area TA, and islimited to the partial width of each of four sides of the opposing basesubstrate 300. A portion of the dead area on the side on which the touchpad portion 370 is located may occupy a relatively wide area.

Although the drawing illustrates an example in which two touch padportions 370 are provided on the upper side at opposite side positions,the disclosure is not limited thereto, and a single touch pad portion370 may be centrally provided on the upper side. In addition, the touchpad portions 370 respectively have therein a plurality of touch pads 360a and 360 b, and are connected to the routing wires 350 a and 350 b,which are respectively connected to the transmission parts Tx and thetransport parts Rx.

In addition, in the flexible display of the present disclosure, thetouch pad portion is connected to a dummy pad portion (not illustrated)of the organic light-emitting array and the thin-film transistor (TFT)array via an anisotropic conductive film when the organic light-emittingarray and the touch electrode array are bonded to each other.

Meanwhile, the touch substrate of the present disclosure includes firstand second transparent conductive layers 322 and 332 in the form ofislands, in order to increase the touch sensitivity of the touchsubstrate. The first and second transparent conductive layers 322 and332 are respectively provided at the intersection of the first directionand the second direction and the intersection of the third direction andthe fourth direction of the touch wires 321 and 331 in the block-shapedtransmission part Tx and transport part Rx. The island-shaped first andsecond transparent conductive layers 322 and 332 are electrically incontact with the touch wires 321 and 331.

In addition, the first and second transparent conductive layers 322 and332 are formed of a material such as, for example, indium tin oxide(ITO), indium zinc oxide (IZO) or indium gallium zinc oxide (IGZO).

Although the first and second touch wires 321 and 331 are formed oflow-resistance metal and thus have the effect of reducing lineresistance and RC delay, the touch wires in the area where a touchactually occurs occupy only a small portion of the touch area, and thusvariation in the amount of charge of a touch object is small, which maymake it difficult to detect whether or not a touch occurs. The reasonwhy the first and second transparent conductive layers 322 and 332 areprovided is to ensure easy detection of variation in capacitance withthe touch object (a finger or a pen) by increasing the area of the touchsubstrate that is occupied by an electrode because the widths of thefirst and second touch wires 321 and 331 are small. That is, thetransparent conductive layer has a length and width greater than thewidth of the touch wire so as to cover the intersection of the touchwires.

In the flexible display of the present disclosure, the base substrate100 of the backplane substrate, which includes the thin-film transistorarray and the organic light-emitting array, and the opposing basesubstrate 300, which is opposite the base substrate 100 and includes thetouch electrode array, are bonded to each other via an adhesive layer250.

Other configurations not described with reference to FIG. 5 to 9 will bedescribed below.

The flexible display may include the protective layer 180 and theplanarization layer 190, which cover the second wires 175, the organiclight-emitting diode OLED, which is provided on the planarization layer190 so as to correspond to each sub-pixel and includes the firstelectrode 200, the organic light-emitting layer 220 and the secondelectrode 230, the encapsulation layer 240, which covers the organiclight-emitting diode OLED, the opposing base substrate 300, which isopposite the base substrate 100, the touch electrode array provided onthe base substrate 300, and the adhesive layer 250 between the touchelectrode array and the encapsulation layer 240. In one embodiment, theadhesion layer 1900 of FIG. 3A corresponds to the layer 190. In a secondembodiment, the adhesion layer 1900 corresponds to the combined layers250 and 190. The adhesion layer 1900 can be comprised of a single layeror a stack of various different layers and sublayers. The adhesion layer1900 can be comprised of a single layer or a stack of various differentlayers and sublayers. In one embodiment layer 190 and layer 250 are bothorganic material. They can be composed of one or more layers andsublayers of organic material. In a further embodiment, the layers 190and 250 and thus layer 1900 includes one or more layers or sublayers ofinorganic material. It is not required for all layers and sublayers oflayer 1900 to be organic for the layer 1900 to fall within thedefinition of organic layer in all embodiments.

The encapsulation layer 240 may have an area greater than that of theplanarization layer 190 and may cover the second wires 175 (second dummywires) and slits 100 a of the dummy pixel portion.

Meanwhile, the touch electrode array of the touch substrate may includethe touch wires 321 and 331 and the transparent conductive layers 322and 332, which are provided on the opposing base substrate 300 so as tocorrespond to the active area AA, and may include the plurality of firstand second touch electrodes 320 and 330, which function as thetransmission parts and the transport parts and cross each other.

In addition, although the first and second touch electrodes 320 and 330are respectively the stacks of the metal meshes 321 and 331 and thetransparent conductive layers 322 and 332 in the illustrated example,the disclosure is not limited thereto, and the first and second touchelectrodes 320 and 330 may have a single layer configuration. The metalmesh may be, for example, an Ag—Pd—Cu (APC) alloy or a Mo—Al—Mo alloy.However, the metal meshes 321 and 331, which constitute the first andsecond touch electrodes 320 and 330, are not limited to above enumeratedexamples, and may be replaced with any other low-resistance metal, or ametal alloy or a metal stack thereof.

In addition, the transparent conductive layers 322 and 332 may be formedof a transparent metal oxide layer such as, for example, ITO, IZO, ITZOor IGZO.

Meanwhile, neighboring first touch electrodes 320 are connected to eachother via the bridge electrode 340, which is provided in another layer,at the intersection with the second touch electrodes 330. The bridgeelectrode 340 is connected to the first touch electrodes 320 via acontact recess, which is formed by removing predetermined regions of thefirst touch electrodes 320, with a touch interlayer insulation layer 325on the first and second touch electrodes 320 and 330.

Meanwhile, routing wires 324 may be provided in the same layer as themetal meshes so as to correspond to the dummy pixel DP or the dead area.

Meanwhile, the example of FIG. 11 illustrates that the dummy pixel DPincludes the adhesion recess 1800 a, which is provided in the inorganicinterlayer insulation stack including two or more layers of metal(wires) under the organic planarization layer 190, so that the materialof the planarization layer 190 is introduced into the adhesion recess1800 a having an inversely tapered shape.

As is apparent from the above description, a backplane substrate and aflexible display using the same according to the present disclosure havethe following effects.

First, based on the observed result in which the interface of an organiclayer with an inorganic layer inside the display exhibits deteriorationin adhesion characteristics upon repeated folding operations, theinorganic layer under the organic layer is provided with a plurality ofrecesses that formed when the contact holes are formed so that theorganic layer is introduced into the corresponding version of thecontact holes in the dummy area and dead area, which in these areasbecome adhesion recesses 1800 a, which may improve adhesioncharacteristics of the interface of the inorganic and organic layers.

Second, each adhesion recess 1800 a has an inversely tapered shape sothat the lower side thereof has a greater diameter than the upper sidethereof. This may structurally prevent the organic layer from peelingoff from the inorganic layer even after repeated folding operations oncethe organic layer has been introduced into the adhesion recesses in theinorganic layer.

Third, an inorganic layer stack in which the adhesion recesses areformed may include metal wires as well as an inorganic insulation layer,which enables the adhesion recesses to be defined in the inorganic layerstack by the difference in selectivity between a plurality of metalwires in the process of forming the contact holes for the pixels andadhesion recesses at the same time, with the same process steps andetching. Accordingly, formation of the inorganic layer stack having theadhesion recesses may be realized at increased reliability withoutincreasing the number of processes.

Although the embodiments of the present disclosure have been describedabove in detail with reference to the accompanying drawings, it will beapparent to those skilled in the art that the present disclosuredescribed above is not limited to the embodiments described above, andvarious substitutions, modifications, and alterations may be devisedwithin the spirit and scope of the present disclosure. Accordingly,various embodiments disclosed in the present disclosure are not intendedto limit the technical sprit of the present disclosure, and the scope ofthe technical sprit of the present disclosure is not limited by theembodiments. Accordingly, the disclosed embodiments are provided for thepurpose of description and are not intended to limit the technical scopeof the disclosure, and the technical scope of the disclosure is notlimited by the embodiments. The range of the disclosure should beinterpreted based on the following claims, and all technical ideas thatfall within the range equivalent to the claims should be understood asbelonging to the scope of the disclosure.

The various embodiments described above can be combined to providefurther embodiments. All of the U.S. patents, U.S. patent applicationpublications, U.S. patent applications, foreign patents, foreign patentapplications and non-patent publications referred to in thisspecification and/or listed in the Application Data Sheet areincorporated herein by reference, in their entirety. Aspects of theembodiments can be modified, if necessary to employ concepts of thevarious patents, applications and publications to provide yet furtherembodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

1. A backplane substrate, comprising: a base substrate in which anactive area having a plurality of sub-pixels is defined in a centerthereof and a dummy pixel portion having dummy pixels is defined alongan edge of the active area; an organic layer positioned to overlay boththe dummy pixels and the sub-pixels; and an inorganic layer stack incontact with the organic layer at least at the location of the dummypixels, the inorganic layer stack having a plurality of adhesionrecesses, in which the organic layer is present.
 2. The backplanesubstrate according to claim 1, wherein the adhesion recesses in theinorganic layer stack have a greater diameter at a lower side thereofthan at an upper side thereof.
 3. The backplane substrate according toclaim 2, wherein the organic layer is in contact with the inorganiclayer stack at a lateral side and at a bottom of each adhesion recess.4. The backplane substrate according to claim 1, wherein the inorganiclayer stack includes: a first wire and a second wire located indifferent layers so as to overlap each other; and a first interlayerinsulation layer located between the first and second wires.
 5. Thebackplane substrate according to claim 4, wherein the adhesion recessprovided in the first wire has a greater diameter than the adhesionrecess provided in the second wire.
 6. The backplane substrate accordingto claim 5, wherein the first wire has a different etch selectivity thanthe second wire.
 7. The backplane substrate according to claim 4,further comprising: a third wire located on an upper side of the secondwire so as to overlap the second wire; and a second interlayerinsulation layer between the second wire and the third wire.
 8. Thebackplane substrate according to claim 7, wherein the adhesion recessprovided in the first wire has a greater diameter than the adhesionrecess provided in the second wire and the third wire.
 9. The backplanesubstrate according to claim 8, wherein the second wire and the thirdwire have a different etch selectivity than the first wire.
 10. Thebackplane substrate according to claim 1, wherein the inorganic layerstack further includes a plurality of sub-adhesion recesses in thesub-pixels.
 11. The backplane substrate according to claim 1 wherein theinorganic layer stack is comprised of a plurality of layers of differentmaterials.
 12. The backplane substrate according to claim 11 whereineach layer in the inorganic layer stack is comprised of an inorganicmaterial.
 13. The backplane substrate according to claim 11 wherein atleast one layer in the inorganic layer stack is comprised of an organicmaterial and at least two layers are comprised of metal that do notinclude an organic material.
 14. A flexible display, comprising: a firstflexible base substrate in which an active area having a plurality ofsub-pixels is defined in a center thereof and a dummy pixel portionhaving dummy pixels is defined along an edge of the active area; asecond flexible base substrate configured to be opposite the firstflexible base substrate and having a touch wire; an adhesive layerprovided between the first and second flexible base substrates; anorganic layer provided on at least one of the first flexible basesubstrate and the second flexible base substrate so as to correspond tothe dummy pixels and the sub-pixels; and an inorganic layer stackconfigured to be in contact with the organic layer thereabove over atleast the dummy pixels, the inorganic layer stack having a plurality ofadhesion recesses, in which the organic layer is present.
 15. Theflexible display according to claim 14, wherein the organic layer andthe inorganic layer stack are provided on the first flexible basesubstrate.
 16. The flexible display according to claim 15, wherein theorganic layer and the inorganic layer stack are further provided on thesecond flexible base substrate.
 17. The flexible display according toclaim 14, wherein the adhesion recesses in the inorganic layer stackhave a greater diameter at a lower side thereof than at an upper sidethereof.
 18. The flexible display according to claim 14, wherein theinorganic layer stack includes wires provided in two or more differentlayers, and an interlayer insulation layer provided between the wires.19. The flexible display according to claim 18, wherein the organiclayer is in contact with the inorganic layer stack on a lateral side anda bottom of each adhesion recess.
 20. The flexible display according toclaim 14, wherein the inorganic layer stack further includes a pluralityof sub-adhesion recesses in the sub-pixels.